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K+N AirFilter low RPM Stumble

Old 07-24-2010, 06:37 AM
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K+N AirFilter low RPM Stumble

I have a stock SuperHawk and put a Stage one Dynojet kit in it and ran great. Then Bought a K+N air filter and followed all the instructions and then had a low RPM stumble. Tried leaner and richer needle postion, richened the mixture screws-all with no real change. Carberation is not clean 1000-4000 RPM then cleans up after that. Any one else have this problem? am I needing a richer pilot jet? Any help is appreciated thanks Jon
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Old 07-24-2010, 06:38 AM
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What you "need" is to put the OEM filter back in. I had the same issue until I put the original filter back in.
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Old 07-24-2010, 07:12 AM
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It's a well known condition with K&N filters... Either spend a lot of time and money "fixing" it... Or stick the stock filter in there...
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Old 07-24-2010, 08:43 AM
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I was afraid of that, so putting in a set of 48 slow jets won't fix it? Thanks for the reply, Jon
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Old 07-24-2010, 09:13 AM
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Do the research on this forum... Then make your decision...
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Old 07-24-2010, 09:44 AM
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I had the same issue -had to start over with the jetting starting with the main jet- I used the factory pro kit - took a lot of work and trying out the differant jets as per the instructions from factory pro - still working on the low end to fine tune it but the stumble and deceleration popping are all gone and the top end is way stronger.
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Old 07-24-2010, 10:11 AM
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Anyone want to buy a K&N filter cheap? It has less than 2000 miles on it.
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Old 07-24-2010, 10:49 AM
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To me the VTR is about low end, sounds like you can't have your cake and eat it to so any one want to buy a K+N with less than 100 miles?....
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Old 07-24-2010, 11:38 AM
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Originally Posted by jonymo View Post
To me the VTR is about low end, sounds like you can't have your cake and eat it to so any one want to buy a K+N with less than 100 miles?....
The old K&N filter saga still rears its ugly head.
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Old 07-24-2010, 12:23 PM
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Originally Posted by jonymo View Post
To me the VTR is about low end, sounds like you can't have your cake and eat it to so any one want to buy a K+N with less than 100 miles?....
Unfortunately it seems the market is flooded with low mileage K&N filters... Wonder why...
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Old 07-27-2010, 10:41 AM
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So while waiting for a new OEM air filter to come in I continued with the rejet...
Dynojet main 180 front 185 rear
Dynojet stage one needle 5th clip
slow jet #48
fuel screw out 2 1/2 turns
Stock exhaust

Bike still has a slight stumble around 3500 RPM but much more improved, anyone want to comment on next possible step(other than sell the K+N)?try #50 slow jet? adjust mixture screw? Needle?
Thanks Jon
PS. Great website here and thanks for the help, I just downloaded the Shop manual.
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Old 07-27-2010, 10:44 AM
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so does that mean at high elevations where the air is thin a k&n filter will help from running rich?
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Old 07-31-2010, 06:08 PM
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Had the same problem, put on stock filter and now runs better.
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Old 08-02-2010, 06:53 AM
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The #50 pilot jets were much too rich when I had the stock pipes and a K+N. I ended up with #48's, 1.5 turns out. There are a range of settings that work for VTR's but each bike seems to have its quirks. What helped me most was information from a guy who knew what he was doing when he had my bike on a dyno with an exhaust gas analyzer.
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